In general, permanent waving of human hair is achieved by chemically breaking the sulfur-to-sulfur or disulfide cystine bonds occurring naturally in human hair and then reforming the cystine bonds while the hair is wrapped or curled on rods. The sulfur-to-sulfur cystine bonds in human hair maintain the hair in a naturally straight or curly configuration and, in order to permanently reshape the hair into a lasting, different configuration, a significant percentage of the sulfur-to-sulfur bonds must be broken and then reestablished after the hair is reconfigured in a desired position, such as wrapped around a suitable mandrel or roller. In general, the sulfur-to-sulfur cystine bonds are broken with a waving lotion composition, containing a reducing agent, and after the hair is wound into a curl formation around a rod or roller, the sulfur-to-sulfur cystine bonds are relinked or reestablished while the hair is in the curled formation by contacting the hair, in the new formation, with an oxidizing agent, such as hydrogen peroxide or a water-soluble bromate.
Waving lotions capable of breaking sulfur-to-sulfur cystine bonds in hair can include one or more reducing agents such as cysteine; cysteamine; acidic sodium hyposulfite; ammonium or sodium bisulfite; thioglycerol; thiolactic acid; thioglycolic acid or its salts, e.g., a thioglycolate, or a dithioglycolate; thiochloline or its salts; a monothioglycolic acid ester; N-acetylcysteamine; cysteamine; or combinations thereof. Examples of prior art reducing agents are disclosed in the following.
As set forth in U.S. Pat. No. 5,116,608, others have used a reducing agent composition that is a quaternary ammoniomercaptan, such as thiochloline, or its salts, together with a second reducing agent, such as thioglycolic acid, cysteamine or cysteine. Also, an N-acylcysteamine HSCH.sub.2 CH.sub.2 NH--COR(R=2-10 C alkyl), as a hair-reducing compound, has been used together with another reducing agent selected from the group consisting of cysteine, acidic sodium hyposulfite, sodium bisulfite, thioglycerol, and thiolactic acid, as disclosed in Japanese Pat. HEI 2-53714. Miyazaki et al. U.S. Pat. No. 4,139,610 discloses a combination of cysteine and N-acetylcysteine. This Assignee's Nandagiri et al. U.S. Pat. No. 5,260,054 discloses cysteamine as a reducing agent, and Showa Japanese Pat. 57062217 (Application No. 55-136857) discloses cysteamine together with an optional second reducing agent. U.S. Pat. No. 5,165,427 discloses cysteinamide as a reducing agent. U.S. Pat. No. 5,223,252 discloses a combination of a thioglycolate and cysteine at a pH of 7.5 to 9.5.
Kubo et al. U.S. Pat. No. 5,352,443) disclose the use of compounds capable of forming an alpha, beta unsaturated ketone-type structure for improving wave efficiency and reducing odor with thioglycolate ester waves. J. March, "Advance Organic Chemistry", John Wiley, N.Y., p. 1061 (1985) clearly states, and it is generally known to those skilled in the art, that poly-phenols with substitutions at the ortho and para positions are easily oxidized to the type of structure described by Kubo et al. by exposure to weak oxidizing agents, such as air. In fact, examples in Kubo et al. include only ortho and para substitutions. Those poly-phenols which are meta substituted, such as those disclosed in this application, require much stronger oxidizing conditions in order to form such alpha, beta unsaturated ketone-type structures.
The reducing action of mercaptans on keratin is due mostly to the dissociated form of the thiol groups, the thiolate anion. "Acid" permanent waves sufficiently curl hair at a lower pH compared to alkaline permanent waves, because the waving agents in these permanent waves have low pKa values and thus exist predominantly in dissociated (thiolate) format a pH approaching neutral. Hence, the pKa value shows that some mercaptans are efficient at high pH while others with a low pKa value and high ionization constant are efficient at lower pH values. Therefore, it is generally understood, by those skilled in the art, that acceptable waving efficiency is usually obtained by working near the pKa of the active reducing agent. For example, it is well known that the alkaline salts of thioglycolic acid, e.g., the ammonium salt of thioglycolic acid (pKa=10.4) has acceptable waving efficiency only if the pH of solution exceeds 9, see Zviak, Charles, The Science of Hair Care, Permanent Waving and Hair Straightening, p. 191, 1986; while amides such as thioglycolamide (pKa=8.4), and esters such as glycerol thioglycolate (pKa=7.8) give acceptable waving efficiency at neutral.
Different reducing agents are effective to break the cystine bonds that cross-link human hair protein at different pHs. Generally speaking, the acid permanent wave compositions having lower pH values and include reducing agents such as bisulfites, e.g., ammonium bisulfite, or glycerol monothioglycolate, capable of breaking the sulfur-to-sulfur cystine bonds within lower pH ranges, whereas the alkaline permanent wave compositions, having pHs in the range of about 7.5 to 9.5, require an alkaline salt of thiglycolic acid so that the alkali can penetrate and swell the hair shaft for easier penetration of the reducing agent in order to break the sulfur-to-sulfur cystine bonds.
The use of diammonium dithiodiglycolate in acid or alkaline permanent wave lotions allows greater flexibility in processing time because it minimizes the possibility of overprocessing. This is due to the fact that the reaction of Ehioglycolic acid (TGA) with hair keratin is an equilibrium process. Thus, by including diammonium dithiodiglycolate (oxidized TGA) in the wave lotion, the rate of the reaction of the thioglycolic acid with hair keratin is decreased and the reaction prevented from going to completion.
Generally, the reducing agent lotion is applied to the hair by first shampooing the hair and then applying the reducing agent lotion to the hair, either before or after the hair is wrapped around suitable rollers. Once it is determined that the reducing agent has been in contact with the hair for a sufficient time period, the hair is rinsed thoroughly with water while still on the rollers or rods, and, while the hair remains on the rollers or rods, a neutralizing agent is applied to oxidize and reform the sulfur-to-sulfur bonds while the hair is in the new, rolled configuration. The neutralizing agent contains an oxidizing agent, such as hydrogen peroxide or a bromate salt, in order to reestablish the sulfur-to-sulfur bonds to leave the hair in a relatively permanent, e.g., 2-4 months, new configuration. The rods are removed before or after rinsing out the neutralizing agent.
When the reducing agent lotion is applied to sections of the head prior to rolling that portion of the hair onto the rods, it is called a lotion wrap, whereas when the hair is rolled on the rods or rollers first and then the lotion applied onto all of the hair after rolling, this is called a water wrap. The timing for the reducing agent to be in contact with the hair for a lotion wrap is begun from the time that all rods are on the head, and the timing for a water wrap begins from the time that the lotion application is completed. The capability of using a water wrap is clearly more desirable since the lotion is applied to the entire head of hair all at once in a short period of time and can be rinsed from the hair all at once to provide a more uniform reducing agent contact time for all of the hair.
It is well known in the art of hair permanent waving that the above-described reducing agents used in permanent waves to alter hair configuration result in a characteristic unpleasant odor in the hair. The intensity and duration of this unpleasant odor is formula dependent, depending, in particular, on the reducing agent used in the waving process. The conventional waving agents that are most widely used are ammonium thioglycolate, glycerol monothioglycolate (GMT), sodium or ammonium bisulfite, and cysteamine. All of these reducing agents leave residual odor on the hair after reaction with the hair that lasts from a day to one or two weeks. Some of the factors that play a role in the amount of odor left in the hair include the concentration and type of reducing agent, and the pH of the waving lotion. Some of the reducing agents are inherently more odoriferous than others. For example, it is widely known that cysteine hydrochloride is less odoriferous than GMT and the odor of sodium bisulfite is different and sometimes less objectionable than the mercaptans (thioglycolates).
The thiol reducing agents, such as ammonium thioglycolate, ammonium dithioglycolate, glyceryl monothioglycolate, and the like, produce malodor due to the formation of disulphides as shown below EQU K--S--S--K+2R--SH.fwdarw.R--S--S--R+2K--SH
The reducing agent step of the permanent waving process forms cleaved disulfide (sulfide) hair sites, and other reaction products. The cleaved disulfide (cysteine) hair bonds having reactive sulfur sites are then oxidized to reestablish the hair bonds in the new hair configuration. Oxidation of the hair sulfur bonds present after reducing agent contact results in reestablished disulfide hair bonds, as well as other side reactions products that are odoriferous.
Post-perm odor has been cited by clients as one of the major drawbacks of permanent waving. Many attempts have been made by formulators to address this odor problem with only limited success. For example, in U.S. Pat. No. 5,223,252, Kolc, Abbott, and Nandagiri disclose a reducing agent composition including a combination of ammonium thioglycolate and cysteine-free base to reduce processing odor and post-perm odor while maintaining all other performance characteristics. In a Japanese patent application 3-271214, Segawa et al. disclose a post-perm treatment composition containing acids to reduce the odor of cysteamine waved hair.
Major marketers of permanent wave products in the United States have attempted to minimize the odor problem by using fragrances in the reducing agent-containing wave lotion and/or in the oxidizing agent-containing neutralizing composition.
While not being bound to any specific theory on the mechanism of action, it is theorized that one of the reasons why there is persistent post-perm odor is due to certain odoriferous residues formed by reaction of hair aldehydes with the reducing agent. It is theorized that these residues are left in the hair after the waving process as a result of being chemically bound to hair protein or as a result of the residues being trapped within the hair matrix. Malodor is given off from these residues when the hair is wetted. Over time, with repeated shampooing of the hair, these residues are released from the hair leaving the hair pleasant-smelling again.
Addressing this problem by simply fragrancing the hair, in an attempt to mask the unpleasant odor, is not effective since the masking fragrance is not long-lasting and does not prevent or reduce the formation of the odoriferous reaction products resulting from the reaction of newly formed hair aldehydes with reducing agent residue trapped in the hair. We have found that polyhydric phenols, particularly resorcinol and its derivatives, unexpectedly reduce the above-mentioned post-perm odors. It is theorized that the polyhydric phenols, used in accordance with the present invention, react with the hair aldehydes to prevent reaction between the reducing agent and hair aldehydes. Surprisingly, the polyhydric phenols are substantive to the hair so that the polyhydric phenols continue to react with newly formed hair aldehydes long after the permanent waving process is completed, even after repeated shampooing of the hair.
Sufficient polyhydric phenol remains substantive to the hair to continue reacting with newly formed hair aldehydes, thereby maintaining the hair essentially odor-free by preventing the newly formed hair aldehydes from reacting with any reducing agent that is trapped within the hair matrix. This odor-reducing potential is maximized when applied to the hair both before the waving lotion and after rinsing the neutralizer from the hair. Tests have shown the presence of the polyhydric polyol in hair after five shampoos, as set forth in Table VIII, infra.
The polyhydric polyols, such as resorcinol or resorcinol derivatives, contained in the compositions of the present invention are effective when applied to the hair at any of the above-described stages of the permanent waving process: (1) before contact with the waving lotion; (2) together with the waving lotion; (3) after contact with the waving lotion, and before rinsing; (4) after waving lotion contact and after rinsing, but before contacting the hair with the neutralizer (oxidizing agent-containing solution); (5) immediately after neutralization; and/or (6) long after neutralization; regardless of the particular reducing agent contained in the waving lotion. The compositions and methods of the present invention are particularly effective to prevent post-perm odor resulting from a cysteamine-containing permanent wave lotion, but also are effective to reduce odor resulting from contacting the hair with any other reducing agent that is reactive with hair aldehydes.